Grinding machines simultaneously working both surfaces of a continuous ribbon of glass



June 27, 1961 A. LAMESCH ETAL 2,989,826

GRINDING MACHINES SIMULTANEOUSLY WORKING BOTH SURFACES OF A CONTINUOUS RIBBON 0F GLASS Filed March 8, 1957 3am J K F FORzEYS United States atent 2,989,826 Patented June 27, 1961 [ice This invention relates, in the manufacture of flat glass, to the grinding of glass sheets by the process called twin grinding. That process involves the simultaneous grinding of opposite faces of the glass sheet by means of opposed, rotary tools called grinders, disposed in pairs, each pair including an upper and a lower grinder between which the glass sheet progresses. The grinders include an annular grinding face to the inner circumference of which the abrasive material is introduced.

It has been established that the glass sheet sags of its own weight within the lower grinder to an extent which is capable of breaking the sheet.

It has heretofore been proposed to overcome that difficulty by providing the lower grinding head with an internally located annulus capable of supporting the sheet as it travels between the opposite sides of the grinding annulus. That proposal is embodied in the application of Robert Touvay, Serial No. 455,293, filed September 10, 1954, now Patent No. 2,788,619. That device is advantageous but has not completely solved the problem of equalizing the wear of glass and grinder with the wear of the inner supporting annulus and glass.

It is an object of this invention to provide the lower twin grinder with a support capable of maintaining the portion of the glass within the lower annulus on a level with the abrasive face of the grinder, and which does not put strain on the glass due to a different rate of wear.

The objects of the invention are accomplished by providing the lower grinding head, toward its center, with a supporting means for the glass sheet which rotates with the grinding head and which is composed of a material having properties of hardness, compared to those of the grinding head, which are calculated, taking into consideration the differences of linear speed between it and the grinding faces, so that the progressive Wear remains substantially the same. By this means the support remains constantly on the same level as the grinding face of the grinding annulus and assures the permanent support of the glass sheet.

The above and further objects and novel features of the present invention will more fully appear from the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not intended as a definition of the limits of the invention. Reference for this latter purpose being had primarily to the appended claims.

In the drawings, wherein like reference characters refer to like parts throughout the several views,

FIG. 1 is a vertical section through the lower of a pair of twin grinders containing the invention.

FIG. 2 is a plan view of the same grinding tool with parts broken away.

FIG. 3 is a fragmentary view in vertical section through the grinding tool, the section being taken along the line 33 of FIG. 2.

In the drawings the numeral 1 refers to the main support of the grinding head which is to be mounted on the vertical rotatable shaft, not shown. That collar 1 has an axis xx and the parts which are hereinafter described are mounted symmetrically with respect to that axis. On

the collar 1 there is an outstanding flange 2 to which a metal plate 3 is attached by bolts 12, which supports at its periphery the grinder support 4 and the grinding tool or head 5 the upper surface 8 of which constitutes the grinding face, which is annular.

The novel central support includes a metal ring 7 which has upstanding inner and outer flanges. This ring 7 is mounted on plate 3 by supporting arms 10 which are connected by bolts 11 to tabs 9 which project from the ring.

The novel self-equalizing support is composed of nar-.

row pieces of wood 13 set symmetrically about the axis xx' in a plurality of spaced inner and outer rows, as shown in the drawing. They may be composed of a single row or of a plurality of rows. They are set within the inner and outer flanges of ring 7 in plaster 14 which holds them in vertical position. The grinding faces 8 are frequently composed of cast iron, sometimes of other materials, but the present construction is capable of equalizing itself to the wear of such grinding materials against the glass. If the total wear be composed of the wear of the glass itself plus the wear on the grinding face 8, the total wear of the inner support of plaster and wood will equalize itself even though the linear speed between the annulus 5 and the annulus 6 is very different. The preferred Wood is one having medium hardness, for instance willow. The wooden plates 13 may be in the form of parallelepipeds, vertically disposed, and, preferably, provided with holes 15 into which the plaster enters at the time of molding. A wooden ring constituting a single plate or concentric wooden rings may replace the several wooden plates, but a plurality of plates are satisfactory and easier to make and assemble.

Instead of wood pieces in plaster the support may be made of saw dust (for instance 5 to 20%) mixed with magnesian cement or Portland cement, stucco or plaster or similar material.

The main advantage of the invention is that the breakage of glass between the twin grinders due to distortion within the annuli is reduced or totally eliminated. This represents a very material economic advantage to the glassmaker. From the technical viewpoint, an inexpensive automatic equalization of the support to the level of the grinder is achieved.

As many apparently widely different embodiments of the present invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments.

What is claimed is:

1. Apparatus for the surfacing of glass comprising a surfacing tool adapted to be applied to the lower face of a horizontally aligned glass object, said tool having an annular working face aligned in a plane and adapted to work against the glass, a support for the glass located radially inwardly of the annular working face, said internal support comprising wooden blocks imbedded in a binder of plaster, said internal support having a glasscontacting face aligned in the same plane as the face of the annular working face, and means to attach the tool to means for imparting rotation thereto, the support having an upper face contacting with the glass sheet which remains constantly substantially aligned in the plane of the working face of the surfacing tool, due to the fact that the material constituting the support has a hardness which is sufliciently lower than that of the surfacing tool so that, taking into account the differences in the linear speeds of the working surface of the tool and of the support, the progressive wear on the tool and on the support remains substantially the same.

2. The apparatus of claim 1 in which the support ineludes at least one narrow strip of wood set on edge and mounted in a block of the said binder.

3. An apparatus according to claim 2 wherein the strips are formed with apertures so that the binding material may penetrate therein.

4. The apparatus of claim 1 in which the support includes a series of wooden strips set edgewise in a circle about the axis of the tool in a block of the said binder.

5. The apparatus of claim 1 in which the support includes a plurality of series of wooden strips set edgewise in concentric circles about the axis of the tool in a block of the said binder.

6. The apparatus of claim 5 in which the strips are parallelepipedic.

7. The apparatus of claim 1 in which the wood is willow.

8. Apparatus for the surfacing of glass comprising a surfacing tool adapted to be applied to the lower face of a horizontally aligned glass object, said tool having an annular working face aligned in a plane and adapted to work against the glass, 21 support for the glass located radially inwardly of the annular working face, said internal support having its glass-supporting surface consisting essentially of a plurality of unitary elements of wood bound in a matrix of cement, said cement binder having hardness less than the hardness of the glass and the working tool, and of the order of hardness which is represented by magnesium cement, Portland cement, stucco, and plaster.

References Cited in the file of this patent UNITED STATES PATENTS 54,535 Harrison May 8, 1866 342,493 Badger May 25, 1886 451,327 Klar Apr. 28, 1891 1,729,498 Waldron Sept. 24, 1929 2,673,428 Cook Mar. 30, 1954 

